Not a HASH reference error

briandanderson1977 has asked for the wisdom of the Perl Monks concerning the following question:

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Re: Not a HASH reference error by perlfan (Parson) on Feb 24, 2016 at 20:07 UTC
In line 55, `my $type_hash = $hashref->{$type};`, you are not checking to make sure that `$hashref->{$type}` exists as an entry or that what's in there is a hash reference. The answer to you question would be more clear if we knew what `$hashref` looks like and the value of `$type` when it fails.	[reply] [d/l] [select]
Re^2: Not a HASH reference error by briandanderson1977 (Novice) on Feb 24, 2016 at 20:13 UTC
Okay, I can go ahead and find that, but it is failing at line 56, not 55. Is that significant? Thank you for the reply.	[reply]
Re^3: Not a HASH reference error by davido (Cardinal) on Feb 24, 2016 at 20:19 UTC
The significance is that line 56 is the earliest point at which Perl discovers there's a problem with line 55. Line 55 grabs the value of a hash key. In this case, that hash key does not contain a hash reference (maybe doesn't exist at all). But this is no problem for Perl. If the key doesn't exist, then the value is `undef`. If it exists but isn't a hash reference, it still causes no problem for line 55. In line 56 you then try to dereference that value as though it were a hash. If the value was `undef`, that clearly cannot be dereferenced. And if the value was defined, but wasn't a hash ref, you also cannot dereference it as a hash. So at this point Perl has no idea what to do, and complains. Dave	[reply] [d/l] [select]
Re^4: Not a HASH reference error by briandanderson1977 (Novice) on Feb 24, 2016 at 20:35 UTC
Re^5: Not a HASH reference error by davido (Cardinal) on Feb 24, 2016 at 22:24 UTC
Some notes below your chosen depth have not been shown here
Re: Not a HASH reference error by mhearse (Chaplain) on Feb 24, 2016 at 20:33 UTC
Try dumping your hashref. It may not be what you think it is: `use Data::Dumper; print Dumper($hashref);` [download]	[reply] [d/l]
Re^2: Not a HASH reference error by briandanderson1977 (Novice) on Feb 24, 2016 at 20:44 UTC
Okay, where should I put that? Should that be at the top of the perl script or in lines 41 or 55? Thanks	[reply]
Re^3: Not a HASH reference error by briandanderson1977 (Novice) on Feb 24, 2016 at 20:58 UTC
Actually I think I got it. Here is the output: /www/configs/DB2/HLBROKDB/scripts/ScriptConfig.Driver.sh /www/configs/ +DB2/HLBROKDB/config/ScriptConfig.HLBROKDB-PROD.xml prodwxbat204as1l Remove control-Ms from config script /www/configs/DB2/HLBROKDB/config/ +ScriptConfig.HLBROKDB-PROD.xml ... Uncataloging items in /www/configs/DB2/HLBROKDB/config/ScriptConfig.HL +BROKDB-PROD.xml main::awc_db2_mgmt_kick running uncatalog for dcs entries $VAR1 = { 'db' => { 'HLBROKDB' => { 'node' => 'HLBROKDB' } }, 'dcs' => [ {} ], 'node' => { 'HLBROKDB' => { 'server' => 'produdbhlbrokdb', 'port' => '54042' } }, 'changeLog' => [ 'Created by Praveenkumar Sampath on 2015-01- +06 05:05:59' ] }; Not a HASH reference at /www/was50/bin/awc_db2_mgmt.pl line 58. /www/was50/bin/awc_db2_mgmt.pl failed: Please investigate. [download] 47 # OUTPUT returns true/false that the specified db2 configuration f +ile could be processed appropriately for the given action. 48 my $log_pre = whatsub(); 49 my ($action,$hashref,@type_order) = @_ or (warn "$log_pre +Invalid arguments" and return 0); 50 51 # Iterate over the configuration types listed in @type_ord +er 52 foreach my $type (@type_order) { 53 print "$log_pre running $action for $type entries\ +n"; 54 # Iterate over all items of that type 55 use Data::Dumper; 56 print Dumper($hashref); 57 my $type_hash = $hashref->{$type}; + #shortcut to smaller hash 58 foreach my $item (keys %{$type_hash}) { 59 print "$log_pre running $action for $type +$item\n"; 60 my $item_hash = $type_hash->{$item}; + #shortcut to smaller hash 61 #Add values for type and action into the h +ash 62 $item_hash->{'name'} = $item; 63 $item_hash->{'type'} = $type; 64 $item_hash->{'action'} = $action; 65 print Dumper($hashref); 66 #execute action for the individual configu +ration 67 unless (db2_mgmt_cat(\%{$item_hash})) { 68 #unless (db2_mgmt_cat(\%{$type_hash})) { 69 # Return false if the action could + not be completed successfully. [download]	[reply] [d/l] [select]
Re^4: Not a HASH reference error by poj (Abbot) on Feb 24, 2016 at 21:32 UTC
Re^2: Not a HASH reference error by briandanderson1977 (Novice) on Feb 26, 2016 at 19:11 UTC
Okay, so latest on this saga. I found out that on an older version of Linux running an older version of perl (v5.8.8), I get a warning but the command still executes: Pseudo-hashes are deprecated at /www/was50/bin/awc_db2_mgmt.pl line 56. Now, on a more recent version of Linux running a newer version of perl (v5.10.1), this just blows up. No warning, just errors out. UGGGH HELP!!!	[reply]
Re^3: Not a HASH reference error by poj (Abbot) on Feb 26, 2016 at 20:15 UTC
If you know the pseudo-hashes are empty of data then a simple check and skip might suffice `foreach my $type (@type_order) { print "$log_pre running $action for $type entries\n"; # Iterate over all items of that type my $type_hash = $hashref->{$type}; next unless ref($type_hash) eq 'HASH'; # <-- add` [download] If you are not sure then use `foreach my $type (@type_order) { # Iterate over all items of that type my $type_hash = $hashref->{$type}; if ( (ref($type_hash) eq 'ARRAY') && (@$type_hash<2) ){ print "Skipping empty pseudo-hash for $type entries\n"; next; } else { print "$log_pre running $action for $type entries\n"; } . .` [download] poj	[reply] [d/l] [select]
Re^4: Not a HASH reference error by briandanderson1977 (Novice) on Feb 26, 2016 at 23:06 UTC
Re: Not a HASH reference error by Your Mother (Archbishop) on Feb 26, 2016 at 19:26 UTC
Sounds to me like you are using XML::Simple and the XML stopped coming exactly as originally expected so the data structures changed type. If so, search around in here or maybe show the invocation for `XMLin` or however you are using it.	[reply] [d/l]
Re^2: Not a HASH reference error by briandanderson1977 (Novice) on Feb 26, 2016 at 23:05 UTC
Yes, we are using XML::Simple. I appreciate the feedback, I'll dig into that a little more. Thank you.	[reply]